<template>
  <div :class="classes">
    <label :class="[prefixCls + '-label']" :for="labelFor" :style="labelStyles" v-if="label || $slots.label">
      <slot name="label">{{ label }}</slot>
    </label>
    <div :class="[prefixCls + '-content']" :style="contentStyles">
      <slot></slot>
      <transition name="fade-in">
        <div :class="[prefixCls + '-error-tip']" v-if="validateState === 'error' && showMessage && form.showMessage">{{
          validateMessage }}
        </div>
      </transition>
    </div>
  </div>
</template>
<script>
  import AsyncValidator from 'async-validator'
  import Emitter from '../../mixins/emitter'

  const prefixCls = 'bin-form-item'

  function getPropByPath (obj, path) {
    let tempObj = obj
    path = path.replace(/\[(\w+)\]/g, '.$1')
    path = path.replace(/^\./, '')

    let keyArr = path.split('.')
    let i = 0

    for (let len = keyArr.length; i < len - 1; ++i) {
      let key = keyArr[i]
      if (key in tempObj) {
        tempObj = tempObj[key]
      } else {
        throw new Error('[bin-ui warn]: please transfer a valid prop path to form item!')
      }
    }
    return {
      o: tempObj,
      k: keyArr[i],
      v: tempObj[keyArr[i]]
    }
  }

  export default {
    name: 'BFormItem',
    mixins: [Emitter],
    props: {
      label: {
        type: String,
        default: ''
      },
      labelWidth: {
        type: Number
      },
      prop: {
        type: String
      },
      required: {
        type: Boolean,
        default: false
      },
      rules: {
        type: [Object, Array]
      },
      error: {
        type: String
      },
      validateStatus: {
        type: Boolean
      },
      showMessage: {
        type: Boolean,
        default: true
      },
      labelFor: {
        type: String
      }
    },
    data () {
      return {
        prefixCls: prefixCls,
        isRequired: false,
        validateState: '',
        validateMessage: '',
        validateDisabled: false,
        validator: {}
      }
    },
    watch: {
      error: {
        handler (val) {
          this.validateMessage = val
          this.validateState = val ? 'error' : ''
        },
        immediate: true
      },
      validateStatus (val) {
        this.validateState = val
      },
      rules () {
        this.setRules()
      }
    },
    inject: ['form'],
    computed: {
      classes () {
        return [
          `${prefixCls}`,
          {
            [`${prefixCls}-required`]: this.required || this.isRequired,
            [`${prefixCls}-error`]: this.validateState === 'error',
            [`${prefixCls}-validating`]: this.validateState === 'validating'
          }
        ]
      },
      fieldValue () {
        const model = this.form.model
        if (!model || !this.prop) {
          return
        }

        let path = this.prop
        if (path.indexOf(':') !== -1) {
          path = path.replace(/:/, '.')
        }

        return getPropByPath(model, path).v
      },
      labelStyles () {
        let style = {}
        const labelWidth = this.labelWidth === 0 || this.labelWidth ? this.labelWidth : this.form.labelWidth

        if (labelWidth || labelWidth === 0) {
          style.width = `${labelWidth}px`
        }
        return style
      },
      contentStyles () {
        let style = {}
        const labelWidth = this.labelWidth === 0 || this.labelWidth ? this.labelWidth : this.form.labelWidth

        if (labelWidth || labelWidth === 0) {
          style.marginLeft = `${labelWidth}px`
        }
        return style
      }
    },
    methods: {
      setRules () {
        let rules = this.getRules()
        if (rules.length && this.required) {
          return
        } else if (rules.length) {
          rules.every((rule) => {
            this.isRequired = rule.required
          })
        } else if (this.required) {
          this.isRequired = this.required
        }
        this.$off('on-form-blur', this.onFieldBlur)
        this.$off('on-form-change', this.onFieldChange)
        this.$on('on-form-blur', this.onFieldBlur)
        this.$on('on-form-change', this.onFieldChange)
      },
      getRules () {
        let formRules = this.form.rules
        const selfRules = this.rules

        formRules = formRules ? formRules[this.prop] : []

        return [].concat(selfRules || formRules || [])
      },
      getFilteredRule (trigger) {
        const rules = this.getRules()

        return rules.filter(rule => !rule.trigger || rule.trigger.indexOf(trigger) !== -1)
      },
      validate (trigger, callback = function () {
      }) {
        let rules = this.getFilteredRule(trigger)
        if (!rules || rules.length === 0) {
          if (!this.required) {
            callback()
            return true
          } else {
            rules = [{ required: true }]
          }
        }

        this.validateState = 'validating'

        let descriptor = {}
        descriptor[this.prop] = rules

        const validator = new AsyncValidator(descriptor)
        let model = {}

        model[this.prop] = this.fieldValue

        validator.validate(model, { firstFields: true }, errors => {
          this.validateState = !errors ? 'success' : 'error'
          this.validateMessage = errors ? errors[0].message : ''

          callback(this.validateMessage)
        })
        this.validateDisabled = false
      },
      resetField () {
        this.validateState = ''
        this.validateMessage = ''

        let model = this.form.model
        let value = this.fieldValue
        let path = this.prop
        if (path.indexOf(':') !== -1) {
          path = path.replace(/:/, '.')
        }

        let prop = getPropByPath(model, path)

        if (Array.isArray(value)) {
          this.validateDisabled = true
          prop.o[prop.k] = [].concat(this.initialValue)
        } else {
          this.validateDisabled = true
          prop.o[prop.k] = this.initialValue
        }
      },
      onFieldBlur () {
        this.validate('blur')
      },
      onFieldChange () {
        if (this.validateDisabled) {
          this.validateDisabled = false
          return
        }

        this.validate('change')
      }
    },
    mounted () {
      if (this.prop) {
        this.dispatch('BForm', 'on-form-item-add', this)

        Object.defineProperty(this, 'initialValue', {
          value: this.fieldValue
        })

        this.setRules()
      }
    },
    beforeDestroy () {
      this.dispatch('BForm', 'on-form-item-remove', this)
    }
  }
</script>
